Conductive coating deposition methods

The electroforming process is used for the production of single or low numbers of cavities, as opposed to others requiring many cavities. The process deposits metal on a master in a plating bath. Many proprietary processes exist. The master can be constructed of such materials as plastic, reinforced plastic, plaster, or concrete that is coated with silver to provide a conductive coating. The coated master is placed in a plating tank and nickel or nickel-cobalt is deposited to the desired thickness of up to about 0.64 cm (0.25 in.). With this method, a hardness of up to 46 RC is obtainable. To reinforce the nickel shell it is backed up with different materials (copper, plastic, etc.) to meet different applications. A sufficient thickness of copper allows for machining a flat surface to enable the cavity to be mounted into a cavity pocket. 

Taylor et al.8 were the first to report an electrochemical method for preparation of MEAs for PEMFCs. In their technique, Pt was electrochemically reduced and deposited at the electrode membrane interface, where it was actually utilized as an electrocatalyst. Nation, which is an ion exchange polymer membrane, is first coated on a noncatalyzed carbon support. The Nafion-coated carbon support is then immersed into a commercial acidic Pt plating solution for electrodeposition. Application of a cathodic potential results in diffusion of platinum cations through the active Nation layer. The migrated platinum species are reduced and form Pt particle at the electrode/membrane interface only on the sites which are both electronically and ionically conductive. The deposition of Pt particles merely at the electrode/membrane interface maximizes the Pt utilization. The Pt particles of 2-3.5 nm and a Pt loading of less than 0.05 mg cm-2 were obtained employing this technique.8 The limitation of this method is the difficulty of the diffusion of platinum... 

Extremely low-dimensional conducting nanowires (as small as 3 nm in diameter) for use in nanoelectronics can be produced with the electrospinning technique [103]. Using template methods, insulating PLA fibers with an average diameter of 200-700 nm as core materials were electrospun and subsequently coated with thin 50-100 nm films of polyaniline or polypyrrole by in situ polymer deposition methods. The PLA core fibers decompose upon relatively mild thermal treatment under inert atmosphere, leaving... 

Different approaches to obtaining stable layered stmctures have been proposed. One possibility consists of using a iayer-by-layer deposition method [16], schematically reported in Fig. 1.3. The growth of multilayer films is carried out by alternating the immersion of a solid conducting substrate into a cationic and then an anionic polyelectrolyte solution the excess of weakly adsorbed molecules is washed out at the end of each deposition step and the coating is dried with nitrogen or air flow before the assembly of any new layer. The preparation method is simple and can be easily automatized. 

Glass fibers have also been coated with conductive polymers. Deposition of polyaniline on glass-fiber fabric provided a method for the production of conductive fabrics [75]. The coating was achieved by several cycles of immersion of the fibers in an acid aniline solution followed by drying at 60°C and immersion in an oxidant solution. The mean growth rate of the deposit thickness was reported to be 150 nm per cycle. The conductivity of the coated fabrics reached 0.23 S cm. According to the authors, the adhesion of polyaniline to the substrate seems to be sufficient, since the mechanical properties of composites do not change in comparison to those of untreated fabric. 

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